Shielding rate calculating apparatus, shielding rate calculating method and program

Abstract

One aspect of the present invention is a shielding rate calculation device including a voxel division unit for dividing a Fresnel zone into a plurality of voxels each having a size corresponding to acquisition conditions at the time of acquiring point group data indicating a shielding object in an inter-wireless-station space between a transmission station and a reception station, and a calculation unit for calculating a shielding rate against a radio wave traveling from the transmission station toward the reception station on the basis of a position, a shape, and a size of a shielding voxel, which is a voxel at a position indicated by the point group data, among the plurality of voxels.

The invention claimed is: 
     
       1. A shielding rate calculation device, comprising:
 a processor; and 
 a storage medium having computer program instructions stored thereon, when executed by the processor, perform to: 
 dividing a Fresnel zone into a plurality of voxels each having a size corresponding to acquisition conditions at the time of acquiring point group data indicating a shielding object in an inter-wireless-station space between a transmission station and a reception station; and 
 calculating a shielding rate against a radio wave traveling from the transmission station toward the reception station on the basis of a position, a shape, and a size of a shielding voxel, which is a voxel at a position indicated by the point group data, among the plurality of voxels. 
 
     
     
       2. The shielding rate calculation device according to  claim 1 , wherein a subspace that is the n-th (n is an integer of 1 or more and N or less) closest to the transmission station, among subspaces that are N (N is an integer of 1 or more) spaces obtained by dividing equally the inter-wireless-station space in the direction of from the transmission station toward the reception station, is defined as an n-th subspace, the Fresnel zone included in the n-th subspace is defined as an n-th partial Fresnel zone, and the computer program instructions further perform to determines a size of the voxel in the n-th subspace on the basis of the acquisition conditions and a position, a shape, and a size of the n-th partial Fresnel zone. 
     
     
       3. The shielding rate calculation device according to  claim 2 , wherein a column having a bottom surface perpendicular to a line segment connecting the transmission station and the reception station and approximating the n-th partial Fresnel zone is defined as an n-th approximate column, and the computer program instructions further perform to determines a size of a bottom surface of a voxel in the n-th subspace on the basis of an area of a bottom surface of the n-th approximate column and the acquisition conditions. 
     
     
       4. The shielding rate calculation device according to  claim 3 , wherein the computer program instructions further perform to, with a set of the voxels approximating the n-th approximate column defined as an n-th approximate column voxel set, executes an n-th standardization deformation that deforms a shape and size of a bottom surface of the n-th approximate column voxel set into a reference figure having a same size and shape regardless of the n-th approximate column, and with the shielding voxel after the n-th standardization deformation defined as an n-th shielding voxel, calculates the shielding rate on the basis of an area of a shielding figure that is a figure on the reference figure onto which bottom surfaces of all shielding voxels from a first shielding voxel to an N-th shielding voxel are projected. 
     
     
       5. The shielding rate calculation device according to  claim 1 :
 wherein a point group data acquisition system for acquiring the point group data is provided with a moving body including an emission unit that emits a laser intermittently at a constant cycle while rotating a direction of emission at a constant angular velocity; and 
 wherein the acquisition conditions include information on a movement of the moving body, emission direction information that is information indicating an emission direction of a wave packet of the laser emitted by the emission unit, and emission timing information that is information on emission timing of the wave packet of the laser emitted by the emission unit. 
 
     
     
       6. The shielding rate calculation device according to  claim 1 , wherein the voxel has a bottom surface perpendicular to a line segment connecting the transmission station and the reception station. 
     
     
       7. A non-transitory computer-readable medium having computer-executable instructions that, upon execution of the instructions by a processor of a computer, cause the computer to function as the shielding rate calculation device according to  claim 1 . 
     
     
       8. A shielding rate calculation method, comprising:
 a voxel division step of dividing a Fresnel zone into a plurality of voxels each having a size corresponding to acquisition conditions at the time of acquiring point group data indicating a shielding object in an inter-wireless-station space between a transmission station and a reception station; and 
 a calculation step of calculating a shielding rate against a radio wave traveling from the transmission station toward the reception station on the basis of a position, a shape, and a size of a shielding voxel, which is a voxel at a position indicated by the point group data, among the plurality of voxels.